Geomys bursarius has been collected from a number of Sangamon fossil sites on the Great Plains. Although specific identification of specimens of Geomys from Illinoian faunas is uncertain, the Great Plains Geomys from Sangamon and later deposits probably is referable to the living species as Hibbard and Taylor (1960:165) pointed out. They found no difference between Geomys recovered from the Cragin Quarry local fauna (early Sangamon) of Meade County, Kansas, and the living species Geomys bursarius. Isolated teeth of the same species were collected from the Jinglebob local fauna of Meade County, Kansas (Hibbard, 1955b:206), a fauna of the late Sangamon. Hibbard (1943:240) also recorded the genus Geomys (referable to G. bursarius) from the Rezabek local fauna of Lincoln County, Kansas. According to Schultz et al. (1951:6 and table 1) the genus Geomys occurs in buried or "fossil" soils of Sangamon age, lying just above the Loveland Loess, in Nebraska. No specific localities were given by them, nor were any particular specimens mentioned. Dalquest reported Geomys bursarius from two Sangamon faunas in northern Texas. The species is represented in the Ward Quarry local fauna of Cooke County, Texas (1962a:42), and the Good Creek local fauna of Foard County, Texas (1962b:575).
Geomys bursarius has been reported from Wisconsin fossil deposits of the Great Plains and adjacent areas as follows: Jones local fauna, Meade County, Kansas (Hibbard and Taylor, 1960:64-66); Two Creeks Forest beds of the third interstadial soils formed between Cary and Mankato glaciations, late Wisconsin (Schultz et al., 1951:8 and table 1); Cita Canyon local fauna in the northern part of the Panhandle of Texas (Johnson and Savage, 1955:39); Howard Ranch local fauna of Hardeman County in northwestern Texas (Dalquest, 1965:70); Quitaque local fauna of Motley County, Texas (Dalquest, 1964:501); Clear Creek local fauna of Denton County in north-central Texas (Slaughter and Ritchie, 1963:120); Ben Franklin local fauna, of late Wisconsin beds along the North Sulphur River in Delta County, NE Texas (Slaughter and Hoover, 1963:137); Bulverde Cave (Hay, 1920:140; 1924:247) and Friesenhahn Cave (Tamsitt, 1957:321), both in Bexar County, south-central Texas; Alton, Illinois (Hay, 1923:338-339); Wisconsin drift of Illinois, without mention of specific locality (Bader and Techter, 1959:172); Wisconsin drift of southwestern Wisconsin and northeastern Iowa (Hay, op. cit.:343); Wisconsin drift near Galena, Illinois, and mouth of Platte River in eastern Nebraska (Leidy, 1869:406).
Brown (1908:194) described Geomys parvidens from the Conard Fissure, in northern Arkansas. Hibbard (1958:25) concluded that the Conard Fissure fauna represents a glacial stage, probably the Illinoian, and Hibbard et al. (1965:510-511) regarded the fauna as a composite including both Irvingtonian and Rancholabrean elements. White and Downs (1961:21) considered G. parvidens to be a subspecies of Geomys bursarius.
The first Pleistocene occurrence of Geomys in the southeastern United States is from the Reddick I deposits reported by Gut and Ray (1963:325), who found the remains of Geomys pinetis among the fossils comprising the "rodent beds" of Marion County, Florida. Gut and Ray tentatively identified the beds as Illinoian, but Kurten (1965:219) regarded the Reddick I fauna as early Sangamon. Simpson (1928:2) reported Geomys floridanus [= pinetis] from Saber-tooth Cave deposits of Citrus County, Florida. The Saber-tooth Cave (or Lecanto Cave) local fauna is considered by Kurten (op. cit.:219) also to be a Sangamon deposit. Geomys floridanus [= pinetis] was reported from the Seminole Field deposits by Simpson (1929:563); both Simpson and Kurten (op. cit.:221) agreed that the Seminole Field fauna is mainly late Wisconsin, although sub-Recent fossils occur at the tops of the beds. Ray (1958:430) collected remains of Geomys pinetis from the Melbourne Bone Bed of Brevard County, Florida. The Melbourne local fauna is considered to be from Wisconsin deposits by Kurten (op. cit.:220). The eastern species of Geomys were probably derived from Great Plains stock that reached the southeastern Coastal Plains in early Rancholabrean (Illinoian) time. Presently there is no contact between the eastern and western populations of the genus, and it is assumed that disjunction occurred as a result of Wisconsin glaciation. It is interesting to note that the genus Thomomys occurred in this region at approximately the same time; both genera occur in Saber-tooth Cave deposits.
The genus Pappogeomys is not known from Pleistocene deposits older than the Wisconsin glaciation, but a pre-Pleistocene occurrence in the Benson beds of Arizona (see discussion of the Pliocene above) shows that Pappogeomys had been differentiated by late Pliocene time. The absence of Pappogeomys, beginning in the early Pleistocene and continuing well into the late Pleistocene, is attributed to the southern distribution of the genus, where its range probably was centered on the Central Plateau of México. The paucity of early and middle Pleistocene deposits from this critical region prevents any definite statements about phyletic development within the genus. All of the late Pleistocene records pertain to the subgenus Cratogeomys (long in use as a generic name but in the present paper reduced to subgeneric rank in the genus Pappogeomys). Schultz and Howard (1935:280) found Cratogeomys [= Pappogeomys] castanops in Burnett Cave in the Guadalupe Mountains of south-central New Mexico. The Burnett deposits are probably late Wisconsin (see Schultz and Tanner, 1957:75, for discussion of the age of these deposits based on carbon-14 tests). These writers (loc. cit.) also referred the mandible of a small pocket gopher to the genus Pappogeomys [= subgenus Pappogeomys]. However, neither genera nor subgenera of the tribe Geomyini can be distinguished on the basis of their inferior dentitions. Judging from the distribution of the modern geomyines, it seems unlikely that the subgenus Pappogeomys has occurred beyond its present range in the late Pleistocene; therefore the small mandible is most likely that of a young individual of Pappogeomys castanops. Russell (1960:543) referred specimens collected at San Josecito Cave in Nuevo León, México, to the group of small subspecies Cratogeomys [= Pappogeomys] castanops. Also, Russell (loc. cit.) identified a rostral fragment as of the genus Cratogeomys [= subgenus Cratogeomys] although the fragment had a combination of features different than in any named species of the genus; he did not name the fragment as a new species, preferring to wait for additional material that could clarify its taxonomic relationships.
Hibbard (1955a:52-53) identified Cratogeomys [= Pappogeomys] tylorhinus from the Becerra Superior deposits in the valley of Tequixquic in the northern part of the state of México. The Wisconsin age of these beds suggests an earlier Pleistocene derivation of the gymnurus-group of species.
Several specimens of the subgenus Cratogeomys have been reported from beds of latest Wisconsin (certainly after the glacial maximum) or post-Wisconsin age. Gilmore (1947:158) found fossil remains of Cratogeomys [= Pappogeomys] castanops commonly in Quaternary cave deposits on the mountain slopes in the vicinity of Cuatro Ciénegas, in central Coahuila. These deposits actually may be of post-Wisconsin origin (see discussion above). Alvarez (1964:8) obtained fragments of Cratogeomys [= Pappogeomys] tylorhinus from sub-Recent deposits of Capa III in the Cueva La Nopalera in southwestern Hidalgo, México. Pappogeomys merriami lives in the area today. Mayer-Oakes (1959:373) reported remains of Cratogeomys [= Pappogeomys] merriami from levels eight and eleven of the excavations at El Risco II, in the northern part of Mexico City. The ages of these deposits are unknown to me, but they probably are no older than late Wisconsin with most of the beds dating from the post-Wisconsin.
This genus is not known from the Pleistocene, except for its occurrence in the San Josecito cave deposits of southwestern Nuevo León, México (Russell, 1960:544). Although Orthogeomys does not occur in the immediate vicinity of the cave at the present time, the northern limits of its range is nearby in southern Tamaulipas. The Orthogeomys from San Josecito Cave differs from living species, and has been named Heterogeomys [= Orthogeomys] onerosus Russell (loc. cit.), and is evidently referable to the subgenus Heterogeomys. As mentioned before, the San Josecito Cave local fauna represents deposits of Wisconsin glaciation.